Insects and pests have been a major concern of pet owners for many years. For many years, pesticide-impregnated collars have been worn by domestic animals, including cats. Constant wear increases risk of pet poisoning and strangulation in cats. It would be very advantageous to provide a convenient way to periodically contact an animal, e.g., a cat, with an insect repellent, rather than subjecting the cat to constant contact, while maintaining a sufficient insect repellent dosage such that insects and pests are constantly repelled. In accordance with the present invention, this is accomplished by impregnating a clay litter material with an insect repellent and then coating the impregnated clay litter material with a water-soluble polymer, so that the repellent is volatilized and released from the litter material only when wetted.
Some of the patents that disclose the use of clay as an absorbent pet litter material are as follows: Crampton, et al. U.S. Pat. No. 4,657,881; Stuart U.S. Pat. No. 4,685,420; McFadden U.S. Pat. No. 3,286,691; Japanese published patent applications J5 8009-626, J6 3044-823-A, J6 0094-043-A, J6 3185-323-A, J6 2239-932-A, and J0 1191-626-A; German DE 3620-447-A; Ducharme, et. al. U.S. Pat. No. 4,844,010; Kumar U.S. Pat. No. 4,343,751; and Jaffee, et al. U.S. Pat. No. 4,459,368. The following U.S. Pat. Nos. disclose pet litters that include additives, e.g., polymers for clumping, or odor control additives: Lang 4,736,706; Smith 4,671,208; Stuart 4,685,420, Sowle, et al. 5,014,650; and-Nelson 5,062,383.
As disclosed in the following U.S. Pat. Nos., it is known to add a pesticide to various cat litter materials: Lowe 4,664,064; Hughes 5,386,803; Prine 4,402,756; Schwartz 4,311,512; Stuart 4,685,420; Lowe, et al. 4,721,059; and Koekemoer 3,993,498. As disclosed in the Lowe U.S. Pat. No. 4,664,064, it is known to spray a vapor-producing pesticide directly onto a cat box filler material, such as clay, in an attempt to provide a pesticide vapor above the cat litter material that will bathe the cat in pesticide when the cat urinates in the litter box containing the pesticide-containing litter material. While this technique may be effective for short time periods, substantially all of the pesticide will be vaporized from such surface-treated clay particles in a short period of time, thereby requiring frequent reapplication of pesticide.
U.S. Pat. No. 5,267,532 discloses incorporating pH-indicating dyes into a water-soluble polymeric film covering an inert substrate that is used as a cat litter additive.
In accordance with the principles of the present invention, it has been found that by coating a water-absorbent clay litter material with a film of water-soluble polymer, after impregnating the clay with a vapor-producing insect repellent, the insect repellent will be released only when the repellent-impregnated litter material is wetted, e.g., when an animal urinates or deposits feces on the litter material.